EVENT 333 Female 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 2 | Yasmine Ollerenshaw | 15 | Flitwick | 5:32.70 |
| 2 | 4 | Anabelle Kett | 15 | Co Peterboro | 5:32.14 |
| 3 | 6 | Francesca Barber | 15 | Co Norwich | 5:29.28 |
| 4 | 8 | Hannah Lovelock | 16 | Hitchin | 5:27.44 |
| 5 | 7 | Summer Buckland | 15 | Harlow Pen | 5:29.01 |
| 6 | 5 | Melike Dagdelen | 15 | Putteridge | 5:30.80 |
| 7 | 3 | Lilia Burgoyne | 15 | Co Norwich | 5:32.24 |
| 8 | 1 | I Stratton-Thomsett | 15 | Colchester | 5:37.08 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 10 | Molly Burrows | 15 | Co Peterboro | 5:26.23 |
| 2 | 12 | Charlisse Harding | 15 | Norwich Swan | 5:24.85 |
| 3 | 14 | Esmie Kidman | 18 | West Norfolk | 5:22.84 |
| 4 | 16 | Kate Hopper | 17 | Berkhamsted | 5:19.72 |
| 5 | 15 | Summer Evason | 15 | Watford SC | 5:22.34 |
| 6 | 13 | Amy Meyer | 15 | Biggleswade | 5:22.90 |
| 7 | 11 | Poppy Magill | 16 | Putteridge | 5:26.10 |
| 8 | 9 | Bethany Crawley | 16 | teamipswich | 5:26.53 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 18 | Isabella Porzio | 20 | Putteridge | 5:15.20 |
| 2 | 20 | Amelia Saunders | 16 | St Felix Sch | 5:13.20 |
| 3 | 22 | Sophie Dowding | 17 | teamipswich | 5:07.64 |
| 4 | 24 | Clementine Lovell | 15 | teamipswich | 5:06.40 |
| 5 | 23 | Grace Robinson | 15 | St Felix Sch | 5:06.90 |
| 6 | 21 | Megan Pye | 22 | Co Norwich | 5:09.70 |
| 7 | 19 | Lisa Leinemann | 17 | Chelmsford | 5:14.14 |
| 8 | 17 | Alexa Mann | 18 | Chelmsford | 5:15.90 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 26 | Olivia Minett | 16 | Co Peterboro | 5:03.85 |
| 2 | 28 | Sadie Hunter | 16 | Co Peterboro | 5:00.67 |
| 3 | 30 | Chloe Barnard | 15 | Basildon Ph | 4:58.13 |
| 4 | 32 | Cait Cotter | 17 | Chelmsford | 4:51.40 |
| 5 | 31 | Ruby Wheeler | 18 | Basildon Ph | 4:52.05 |
| 6 | 29 | Lexie O'Connor | 17 | Basildon Ph | 4:59.90 |
| 7 | 27 | Lilly Davis | 17 | Co Peterboro | 5:03.49 |
| 8 | 25 | Annie McLeod | 16 | Putteridge | 5:04.03 |