Do a search / look back on previous threads. Everyone has their own favourite - Charles, Julian, Brian and I will say buy a Scorpion for example and others will favour ribcraft, zodiac, avon etc. We'll be right of course.............
For the use you are talking about I would look for 6.5-7.5m boat, probably secondhand but making sure you get a new tech outboard motor - eg. Optimax, Ficht or HPDI 2 stroke or poss a 4 stroke. Avoid carb/ old efi 2 strokes like the plague.
£25k should buy a tidy Scorpion 7.5m for example which is a good size for cruising but still manageable for launch and recovery. For this size boat you do need a 4x4 for towing and launch/recovery.
They say that the search for a new boat is half the fun of it all so enjoy!