As lee title, looking for a yard with an indoor school win easy reach of M4 J12. Preferably DIY or assisted DIY. Think it's an impossible quest but there might be a hidden gem out there.
Near Junction 12 you have Cullinghood which has indoor and outdoor, Hall place, Hillfields. Then there are other livery yards that have good outdoors; Greenmore, Tidmarsh stud, buckhold and there are some along the A4. If you join the some groups on Facebook ie: Berkshire horse & pony etc... people pop details about livery yards on their all the time.
Although HP have uprights in them its more common than you think and totally acceptable by the local authority and the BHS as long as they are padded. However neither cullinghood or HP are big enough to ride in properly and both have drainage issues in they outdoor. Fairoak would be a better option.