It will be warm tomorrow, and keeping hydrated will be key. From memory the following places will be open when you pass.
Leaving Bushley prompt, there will be shops in Pershore, a couple of service stations about 100m100 metres off route. Tesco at St. Peters - Worcester. Service station on Hylton Road shortly before B-road to Martley. In Martley there is a village shop, Clifton-on-Teme - village shop. Shops in Tenbury (but you're only a couple (or so) km from control by then.) Shop at Shobdon, shops at Eardisley, toll bridge at Clifford did sell ice creams/drinks, DROVERS CYCLES AT HAY-on-WYE., shops in Talgarth (just off route. Shop at Bwlch on A40 Tjunction. But then it's down hill all the way to THE VILLAGE STORES/CAFE at Talybont-on-Usk. Service station and shops just off route at Crickhowell, further shops/services at Abergavenny. Shops just off piste at USK. Services and shops on route in Chepstow, services at Severn View services, chippy in Berkeley sells cold drinks, also shops for early birds (I've always managed to get to the shops there). Control a few km further on. Then next places are likely to be Sainsbury and tesco in Gloucester.
There are too many PHs to list along route, so these are also options to get water or soft drinks.
After Gloucester the options are likely to be restricted, but you're about 15 km from arrivee at that point. The, BP service station a few km north of Gloucester does have a water tap on outside wall.