Hatdknott at that point in the ride is just a complete sufferfest. The year i did it someone had sprayed “Do not get off your bike” on the road coming into the hardest bit, which was the last thought I wanted in my mind at that point!
The Fred Whitton is definitely a big challenge but you also get to ride the most beautiful roads in England which is a major attraction for me.
Dartmoor Classic is great with less steep gradients than the Fred.
Simon Warren’s book of rides round the UK could be worth a look for inspiration: https://www.100climbs.co.uk/books. I’ve done a few and they’ve all been awesome. Obviously he likes his hills so if you want something flatter then the rides around the south east will be more what you are after
Echoing what others have said, Fred Whitton is the best sportive in the UK. Did it last year and was the best day I’ve ever had on the bike, entire local villages come out to support and you really feel the community want the event to be there (in contrast to other events I’ve done).
It’s some of the most spectacular scenery in the UK so the cycling is never boring and all the people doing it are there to enjoy a big day out.
It’s a long way and there are big hills but it’s 100% worth training for and going to have a go with some spinning gears on the bike!
Le Petit Depart, organized by Skipton CC, is an excellent 80 miler around the Yorkshire Dales, following much of the route used by Stage 1 of the Tour in 2014, rolling roads with 3 solid climbs, usually the first weekend in June.