EVENT 504 Mixed 800m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 2 | 2 | Cora PAYNE | 10 | Dunstable | |
| 3 | 4 | Samuel CHILDS | 11 | Berkhamsted | |
| 4 | 6 | Isabella (Izzy) BENDEL | 10 | Aylesbury | |
| 5 | 5 | Matilda TOMKINSON | 11 | Co Milton K | |
| 6 | 3 | Mia MONKSMITH | 12 | Berkhamsted | |
| 7 | 1 | Emilia FACCINI | 13 | Berkhamsted | |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 8 | Clara NEWBY | 12 | Co St Albans | |
| 2 | 10 | Luke TRULL | 12 | Dunstable | |
| 3 | 12 | Max HART | 11 | Verulam | 11:50.00 |
| 4 | 14 | Olivia COOPER | 15 | Dunstable | 11:44.94 |
| 5 | 13 | Lana WAHLBERG | 13 | Amersham | 11:47.56 |
| 6 | 11 | Alexandra STACHURA | 15 | Dunstable | |
| 7 | 9 | Mia ECKLEY | 10 | Co Milton K | |
| 8 | 7 | Freya POTTON | 13 | Co Milton K | |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 16 | Charlotte BARNARD | 13 | Camden Swiss | 11:13.19 |
| 2 | 19 | Evie TRAN | 14 | Camden Swiss | 11:03.38 |
| 3 | 22 | Alice BUCKINGHAM | 11 | Team Luton | 10:38.00 |
| 4 | 25 | Eva CHAMORRO | 13 | Camden Swiss | 10:14.54 |
| 5 | 23 | Heather ELRICK | 15 | Newport Pag | 10:36.20 |
| 6 | 20 | Ashley-Jane ANG | 12 | Camden Swiss | 10:47.00 |
| 7 | 18 | Lucia DAY | 13 | Team Luton | 11:09.00 |
| 8 | 15 | Zara CHAMORRO | 15 | Camden Swiss | 11:34.59 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Club | Time |
| 1 | 27 | Stewart BUTLER | 13 | Dunstable | 9:58.30 |
| 2 | 29 | Lydia SLADE-CARTER | 15 | Co Milton K | 9:57.35 |
| 3 | 34 | Daniel DICK | 17 | Newport Pag | 9:29.17 |
| 4 | 37 | Adam O'NEAL | 16 | Bedford SS | 8:50.20 |
| 5 | 36 | Henry GILLAM | 14 | Camden Swiss | 9:16.90 |
| 6 | 31 | Archie HENDERSON | 15 | Bedford SS | 9:46.00 |
| 7 | 28 | Vincent WUN | 14 | Camden Swiss | 9:57.85 |
| 8 | 26 | Dillan CRONIN | 14 | Bark & Dagen | 10:03.10 |