EVENT 325 Female 400m IM - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 3 | 1 | Lola-Rose Curtin | 15 | Halesworth | 5:37.40 |
| 4 | 3 | Myla Xia | 15 | Royston | 5:36.22 |
| 5 | 2 | Emilia Armstrong | 15 | Stowmarket | 5:37.16 |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 2 | 5 | Alice Wilson | 15 | New Hall | 5:35.00 |
| 3 | 7 | Megan Randall | 15 | Royston | 5:33.23 |
| 4 | 9 | Ava Sims | 15 | Chelmsford | 5:27.14 |
| 5 | 8 | Amber Lyne | 16 | Co Cambridge | 5:27.17 |
| 6 | 6 | Isla Staton | 15 | March | 5:34.54 |
| 7 | 4 | Madison Hicks | 15 | West Norfolk | 5:35.11 |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 11 | Devon O'Neil | 16 | Co Peterboro | 5:24.62 |
| 2 | 13 | Freya Hill | 15 | New Hall | 5:23.72 |
| 3 | 15 | Melike Dagdelen | 17 | Putteridge | 5:21.00 |
| 4 | 17 | Alice Watts | 18 | Co Cambridge | 5:17.98 |
| 5 | 16 | Chloe Cranny | 15 | Epping For't | 5:20.95 |
| 6 | 14 | Megan Barnicoat | 15 | Co Peterboro | 5:22.70 |
| 7 | 12 | Hannah Lovelock | 18 | Hitchin | 5:24.58 |
| 8 | 10 | Caitlin Stockwell | 16 | Co Cambridge | 5:25.24 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 19 | Jasmine Scott | 15 | Co St Albans | 5:16.17 |
| 2 | 21 | Bethany Crawley | 18 | teamipswich | 5:14.93 |
| 3 | 23 | Orlagh Quarrell | 16 | Watford SC | 5:12.30 |
| 4 | 25 | Daisy-Mai Doel | 15 | Basildon Ph | 5:12.04 |
| 5 | 24 | Georgina Hamilton | 18 | Co St Albans | 5:12.30 |
| 6 | 22 | Summer Smith | 15 | Basildon Ph | 5:12.90 |
| 7 | 20 | Isabella Helliwell | 15 | Basildon Ph | 5:16.10 |
| 8 | 18 | Heidi King | 15 | Hemel Hemp | 5:16.23 |
| Heat Number - 5 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 27 | Emma Cushion | 16 | Co Peterboro | 5:10.30 |
| 2 | 29 | Amelia Saunders | 18 | Norwich Swan | 5:09.70 |
| 3 | 31 | Poppy Magill | 18 | Putteridge | 5:07.38 |
| 4 | 33 | Lois Smith | 16 | Basildon Ph | 5:03.08 |
| 5 | 32 | Isla Stewart | 16 | Co Peterboro | 5:07.00 |
| 6 | 30 | Isabella Porzio | 22 | Putteridge | 5:08.92 |
| 7 | 28 | Amelia Porzio | 18 | Putteridge | 5:09.70 |
| 8 | 26 | Nina Allen | 15 | Newmarket | 5:11.46 |
| Heat Number - 6 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 35 | Chloe Butler | 22 | Norwich Swan | 4:58.70 |
| 2 | 37 | Lilly Davis | 19 | Co Peterboro | 4:57.12 |
| 3 | 39 | Amelia Fenner | 16 | Basildon Ph | 4:54.40 |
| 4 | 41 | Jasmine Hall | 16 | Basildon Ph | 4:49.01 |
| 5 | 40 | Sadie Hunter | 18 | Co Peterboro | 4:52.28 |
| 6 | 38 | Summer Evason | 17 | Watford SC | 4:55.41 |
| 7 | 36 | Chloe Barnard | 17 | Basildon Ph | 4:57.80 |
| 8 | 34 | Annie McLeod | 18 | Putteridge | 5:00.13 |