EVENT 333 Female 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | Daisy Jubb | 15 | Co St Albans | 5:36.99 |
| 4 | 3 | Tyra Sajudeen | 15 | Co Cambridge | 5:35.28 |
| 5 | 2 | Florence Whittaker | 15 | Biggleswade | 5:36.95 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 5 | Freya May | 15 | Leiston | 5:33.16 |
| 2 | 7 | Milly Johnson | 15 | West Norfolk | 5:31.53 |
| 3 | 9 | Elena Buckley | 15 | Basildon Ph | 5:28.44 |
| 4 | 11 | Isla Stewart | 15 | Co Peterboro | 5:24.90 |
| 5 | 10 | Caitlin Stockwell | 15 | Co Cambridge | 5:28.34 |
| 6 | 8 | Devon O'Neil | 15 | Co Peterboro | 5:28.96 |
| 7 | 6 | Freya Gyselings | 15 | Co Peterboro | 5:31.67 |
| 8 | 4 | Emily Calvert | 15 | Putteridge | 5:34.61 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 13 | Esmie Kidman | 19 | West Norfolk | 5:22.84 |
| 2 | 15 | Bethany Crawley | 17 | teamipswich | 5:20.82 |
| 3 | 17 | Emma Cushion | 15 | Co Peterboro | 5:19.49 |
| 4 | 19 | Ruby Chapman | 19 | Norwich Swan | 5:18.26 |
| 5 | 18 | Alice Watts | 17 | Co Cambridge | 5:18.45 |
| 6 | 16 | Ruby-May Ciaburro | 15 | Watford SC | 5:20.00 |
| 7 | 14 | Sophie Payne | 23 | Putteridge | 5:22.80 |
| 8 | 12 | Evie Greenhalf | 15 | Co Norwich | 5:24.20 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 21 | Georgina Hamilton | 17 | Co St Albans | 5:13.55 |
| 2 | 23 | Poppy Magill | 17 | Putteridge | 5:11.43 |
| 3 | 25 | Sophie Dowding | 18 | teamipswich | 5:06.46 |
| 4 | 27 | Summer Evason | 16 | Watford SC | 5:04.45 |
| 5 | 26 | Lois Smith | 15 | Basildon Ph | 5:05.79 |
| 6 | 24 | Amelia Saunders | 17 | Norwich Swan | 5:10.50 |
| 7 | 22 | Isabella Porzio | 21 | Putteridge | 5:12.30 |
| 8 | 20 | Megan Pye | 23 | Co Norwich | 5:14.20 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 29 | Amelia Fenner | 15 | Basildon Ph | 4:59.81 |
| 2 | 31 | Sadie Hunter | 17 | Co Peterboro | 4:58.10 |
| 3 | 33 | Lilly Davis | 18 | Co Peterboro | 4:56.20 |
| 4 | 35 | Cait Cotter | 18 | Chelmsford | 4:49.20 |
| 5 | 34 | Jasmine Hall | 15 | Basildon Ph | 4:54.67 |
| 6 | 32 | Chloe Barnard | 16 | Basildon Ph | 4:56.33 |
| 7 | 30 | Lexie O'Connor | 18 | Basildon Ph | 4:58.62 |
| 8 | 28 | Annie McLeod | 17 | Putteridge | 5:00.35 |