EVENT 504 Mixed 1500m Freestyle - Heats
| Heat Number - 1 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 3 | 1 | Lyle SULLIVAN | 12 | | Saffron Wald | |
| 4 | 3 | Ruth BISCOE | 12 | | Team Luton | |
| 5 | 2 | Isabelle WATSON | 11 | | Dunstable | |
| Heat Number - 2 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 2 | 7 | Chloe FINCH | 14 | | Biggleswade | |
| 3 | 10 | Annabel WHETTON | 12 | | Harpenden | 24:05.60 |
| 4 | 12 | Filip BOCHENKO | 13 | | Ealing | 22:49.30 |
| 5 | 11 | Chloe MATTHEWS | 14 | | Linslade | 23:06.00 |
| 6 | 8 | Freya KEELING | 13 | | Hoddesdon | |
| 7 | 6 | Lucy BISCOE | 10 | | Team Luton | |
| Heat Number - 3 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 17 | Emily PALLETT | 13 | | Co Milton K | 21:39.27 |
| 2 | 19 | Tali FROOME | 15 | | Harpenden | 20:22.31 |
| 3 | 21 | Victoria GRANT | 12 | | TigersJersey | 20:05.63 |
| 4 | 23 | Charlotte DIXON | 12 | | Hitchin | 20:01.90 |
| 5 | 22 | Thomas HOGBEN | 13 | | Co Milton K | 20:05.40 |
| 6 | 20 | Adam MESSIS | 14 | | Ealing | 20:10.50 |
| 7 | 18 | Maisie HOWELL | 12 | | Bo Southend | 20:46.09 |
| 8 | 15 | Mark EVENS | 29 | S14 | Hitchin | 22:18.34 |
| Heat Number - 4 |
| Lane | Comp.No. | Name | AaD | Cat | Club | Time |
| 1 | 25 | Megan MCKAY | 16 | | Leighton Buz | 19:58.00 |
| 2 | 27 | Libby FLITTON | 13 | | Dunstable | 19:32.10 |
| 3 | 29 | Samuel CHILDS | 13 | | Berkhamsted | 19:06.32 |
| 4 | 31 | Hayden JOHNSON | 16 | | Biggleswade | 18:25.90 |
| 5 | 30 | Connie FLITTON | 15 | | Dunstable | 18:47.10 |
| 6 | 28 | Evie ARMSTRONG | 13 | | Dunstable | 19:24.18 |
| 7 | 26 | Anna REGAN | 14 | | Bo Southend | 19:46.70 |
| 8 | 24 | Luke TRULL | 14 | | Dunstable | 19:58.36 |