EVENT 509 Female 400m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 2 | 1 | Charlotte Ryan | 25 | S6 | Runnymede | 8:45.70 |
| 3 | 3 | Ida Corcoran | 16 | S9 | Flitwick | 5:56.43 |
| 4 | 5 | Ayla Zolfaghari | 14 | | Epping For't | 4:44.74 |
| 5 | 4 | Lena Crisp | 12 | S14 | Norwich Swan | 5:11.80 |
| 6 | 2 | Florence Richbell | 11 | S12 | Flitwick | 6:55.70 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 7 | Jasmine Scott | 14 | | Co St Albans | 4:43.70 |
| 2 | 9 | Melike Dagdelen | 16 | | Putteridge | 4:42.33 |
| 3 | 11 | Summer Evason | 16 | | Watford SC | 4:40.80 |
| 4 | 13 | Orlagh Quarrell | 15 | | Watford SC | 4:39.46 |
| 5 | 12 | Isabel Thomas | 17 | | Newmarket | 4:40.62 |
| 6 | 10 | Antonia Elias | 16 | | Watford SC | 4:41.90 |
| 7 | 8 | Ella Deaton | 16 | | Newmarket | 4:42.69 |
| 8 | 6 | Ava Turner | 16 | | Basildon Ph | 4:44.62 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 15 | Chloe Cranny | 14 | | Epping For't | 4:37.80 |
| 2 | 17 | Lexie Goodman | 18 | | Basildon Ph | 4:36.90 |
| 3 | 19 | Ruby Chapman | 19 | | Norwich Swan | 4:33.97 |
| 4 | 21 | Amelia Porzio | 17 | | Putteridge | 4:32.58 |
| 5 | 20 | Gabriella Troman | 16 | | teamipswich | 4:33.28 |
| 6 | 18 | Amy Meyer | 16 | | Biggleswade | 4:36.80 |
| 7 | 16 | Francesca Barber | 16 | | Co Norwich | 4:37.80 |
| 8 | 14 | Eleanor McLeod | 17 | | Putteridge | 4:39.42 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 23 | Anabelle Kett | 16 | | Co Peterboro | 4:32.04 |
| 2 | 25 | Sadie Hunter | 17 | | Co Peterboro | 4:28.40 |
| 3 | 27 | Annie McLeod | 17 | | Putteridge | 4:24.92 |
| 4 | 29 | Jasmine Hall | 15 | | Basildon Ph | 4:16.94 |
| 5 | 28 | Ever Ives | 16 | | Hatfield | 4:23.64 |
| 6 | 26 | Alice Weston | 19 | | Watford SC | 4:28.25 |
| 7 | 24 | Summer Smith | 14 | | Basildon Ph | 4:30.50 |
| 8 | 22 | Erin Uttridge | 16 | | teamipswich | 4:32.40 |