Not Competing : 22,34
| Heat Number - 1 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 2 | 1 | Robbie CRUICKSHANKS | 11 | Team Ipswich Swimming | 3:15.25 |
| 3 | 3 | Joshua SPENCER | 12 | City Of Peterborough SC | 3:14.84 |
| 4 | 5 | Tobin SARI | 12 | West Suffolk Swimming Club | 3:14.51 |
| 5 | 4 | Enzo LIM | 12 | Watford SC | 3:14.54 |
| 6 | 2 | James GISBORNE | 12 | Bishops Stortford SC | 3:14.94 |
| Heat Number - 2 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 7 | James CLAY | 12 | Stowmarket SC | 3:14.29 |
| 2 | 9 | Alfie FRANCIS | 12 | Colchester SC | 3:13.26 |
| 3 | 11 | Matthew MONIE | 12 | City of Cambridge SC | 3:12.72 |
| 4 | 13 | Mark MILBURN | 12 | Colchester SC | 3:11.63 |
| 5 | 12 | Colin MOGHINA | 12 | Thurrock Swimming Club | 3:12.49 |
| 6 | 10 | Billy MEAD | 12 | Dunstable SC | 3:13.03 |
| 7 | 8 | Daniel AJETUMMOBI | 12 | Thurrock Swimming Club | 3:13.90 |
| 8 | 6 | Noah CRABB | 12 | Team Ipswich Swimming | 3:14.44 |
| Heat Number - 3 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 15 | Billy KNIBB | 12 | Linslade Crusaders Swimming Club | 3:10.45 |
| 2 | 17 | Daniel HOLLISS | 11 | City of St Albans SC | 3:09.63 |
| 3 | 19 | Max ROBERTSON | 13 | Hatfield SC | 3:08.42 |
| 4 | 21 | Matthew WEIMANN | 13 | City of Cambridge SC | 3:08.27 |
| 5 | 20 | Bradley BORLAND | 13 | Putteridge Swimming Club | 3:08.40 |
| 6 | 18 | Finley COMAN | 12 | Great Yarmouth SC | 3:09.58 |
| 7 | 16 | Brayden DOYLE | 12 | Brentwood SC | 3:10.24 |
| 8 | 14 | Eldrick MANELA | 12 | Stevenage SC | 3:10.73 |
| Heat Number - 4 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 24 | Ethan ANGEL | 11 | Team Ipswich Swimming | 3:06.60 |
| 2 | 26 | Luke TAYLOR | 13 | City of Cambridge SC | 3:04.56 |
| 3 | 28 | Alexander WILLIAMS | 12 | Watford SC | 3:03.69 |
| 4 | 30 | George WILLIAMS | 13 | Harpenden Swimming Club | 3:02.44 |
| 5 | 29 | Ashton NEO | 13 | Linslade Crusaders Swimming Club | 3:03.07 |
| 6 | 27 | Johnny WILDE | 13 | Putteridge Swimming Club | 3:04.10 |
| 7 | 25 | Taylor COE | 13 | Cheshunt Swimming Club | 3:05.53 |
| 8 | 23 | Thomas OWEN | 12 | West Norfolk Swimming Club | 3:07.40 |
| Heat Number - 5 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 32 | Tyler TOMBS | 12 | Chelmsford City SC | 3:01.80 |
| 2 | 35 | James ROTHWELL | 13 | City Of Peterborough SC | 2:59.12 |
| 3 | 37 | Marcus MOSCUZZA | 12 | St Felix School SC (Southwold) | 2:57.34 |
| 4 | 39 | James MARTINEZ | 14 | West Suffolk Swimming Club | 2:56.92 |
| 5 | 38 | Brayden DITCHFIELD-WAT | 14 | Leighton Buzzard SC | 2:56.94 |
| 6 | 36 | Mide OLAJIDE | 13 | Thurrock Swimming Club | 2:57.90 |
| 7 | 33 | Ketan RACH | 13 | Watford SC | 3:01.17 |
| 8 | 31 | Aidan PILCHER | 12 | Team Ipswich Swimming | 3:02.43 |
| Heat Number - 6 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 41 | Louis BYRNE | 14 | City of Cambridge SC | 2:55.63 |
| 2 | 43 | Olivier VEDRENNE | 12 | UEA City of Norwich SC | 2:54.92 |
| 3 | 45 | Joshua STEPHENS | 14 | St Felix School SC (Southwold) | 2:53.80 |
| 4 | 47 | Euan DONALD | 14 | Berkhamsted SC | 2:52.81 |
| 5 | 46 | Harry ARBUTHNOTT | 14 | Harpenden Swimming Club | 2:53.64 |
| 6 | 44 | Samuel RENNIE | 13 | Braintree & Bocking SC | 2:54.70 |
| 7 | 42 | Robert ADDIS | 13 | West Norfolk Swimming Club | 2:55.14 |
| 8 | 40 | Jack BROWN | 14 | City Of Peterborough SC | 2:56.03 |
| Heat Number - 7 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 51 | Edward MERHAN | 12 | West Suffolk Swimming Club | 2:51.40 |
| 2 | 57 | Mattias MORSE | 14 | Hemel Hempstead SC | 2:47.00 |
| 3 | 63 | Harrison JARVIS | 13 | Thurrock Swimming Club | 2:43.33 |
| 4 | 69 | Freddie LAWS | 14 | West Norfolk Swimming Club | 2:38.00 |
| 5 | 66 | Owen WEBSTER | 14 | St Felix School SC (Southwold) | 2:40.64 |
| 6 | 60 | Rhys DAVIDSON | 13 | Team Luton Swimming | 2:45.90 |
| 7 | 54 | Owen THOMAS | 13 | Modernian SC | 2:50.60 |
| 8 | 48 | Harry SWANN | 13 | Lowestoft & Oulton Broad SC | 2:52.79 |
| Heat Number - 8 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 52 | William TOZER | 14 | West Suffolk Swimming Club | 2:51.12 |
| 2 | 58 | Joe COOPER | 13 | Team Ipswich Swimming | 2:46.86 |
| 3 | 64 | Lewis SHAYLER | 14 | Watford SC | 2:43.18 |
| 4 | 70 | Sam WILLIAMSON | 13 | Hatfield SC | 2:33.30 |
| 5 | 67 | Matthew DEBENHAM | 13 | Team Ipswich Swimming | 2:40.19 |
| 6 | 61 | Jack RICHARDSON | 14 | Dunmow Atlantis SC | 2:45.60 |
| 7 | 55 | Yuto WATANABE | 13 | Hatfield SC | 2:50.06 |
| 8 | 49 | Alex GALLAGHER | 14 | Wisbech Swimming Club | 2:52.79 |
| Heat Number - 9 | |||||
| Lane | Comp.No. | Name | AaD | Club/Country | Time |
| 1 | 53 | Samuel BULLINGHAM | 14 | West Suffolk Swimming Club | 2:50.84 |
| 2 | 59 | William ROBINS | 14 | C Beds SS | 2:46.27 |
| 3 | 65 | James DILLON | 14 | Basildon and Phoenix SC | 2:40.70 |
| 4 | 71 | Finn JEFFERY | 14 | St Felix School SC (Southwold) | 2:33.10 |
| 5 | 68 | James QUINN | 13 | St Ives SC | 2:39.20 |
| 6 | 62 | Callum STEDMAN | 14 | Dereham & District SC | 2:43.87 |
| 7 | 56 | Harvey HALL | 14 | Deben SC | 2:48.06 |
| 8 | 50 | Henry KING | 14 | West Suffolk Swimming Club | 2:52.66 |