Went to the Southport Weekender at Finsbury Park last month. There was a bit of old school there and I caught some of Bukem's set, which was decent. I mainly went to see Juan Atkins though and spent most of the time in the Detroit Techno arena.
The big one was Glastonbury, had a great time there and was one of the best ones I've been to as well. I didn't only go for the old school but saw a fair bit, Mark XTC, Altern8, Goldie's 92-94 rave set at Arcadia (the big fire breathing metallic spider) which was nuts. One of the best things I saw was Billy Bunter's acid house set at 4am on Bez's stage, absolutely loved that. Also a special mention to Hacienda Classical, I wasn't sure if I'd like it as I thought it might be a bit gimmicky, but it worked surprisingly well and went down a storm.
Last year Symmetry festival was pretty good for oldskool but thats not on this year I think it may be back on next year. Sunday was superb for oldskool on the Clockwork stage and I was lucky to play with my partner Louise +1 on there.
Freekuency at the beginning of the year in Portugal the last 2 years has been great too a fair bit of oldskool with all sorts of other techno/dnb will deffinately go to that next year.
Glastonbury has its fair share of oldskool in Shanri-La and the Common. Really enjoyed playing on Bloc 9/Brainwash in 2015 and again Brainwash in 2016 ... Brainwash was a micro venue for about 100 people in Shangri-la but they seemed to have done away with the micro venues this year. It was great we had Friday night Techno and Saturday Oldskool/Drum and Bass the sets were recorded and are up on mixcloud
Boomtown seems like the big one coming up there is bound to be lots of oldskool there.