Have you tried somewhere like anglers paradise
I stayed at rookley country park on the I O W few years back in chalet 6 the pond was just the other side of the patio door so was great to do stuff in the day and still do a bit of fishing in the evening, the specimen lake is 1min walk away but that had to be booked I did 3 nights on there but only managed to lose 1 stalking, the misses stayed in the chalet but spent the evenings drinking wine with me
Both lakes are small but well looked after and some stunners in specimen lake
I enjoyed the week and was able to combine fishing and time with misses
Swimming pool and other stuff for your son to do aswell