are these kind of road races fun
yes, most fun you can have on a bike imo
Its a steep learning curve IME, you might find certain courses suit you better than others but you find this out the hard way through racing lots on a variety of courses. You won't find out much though if you go in tired - rest day 2 days before the race, then day before spin out your legs easy. Decent warm up of around 20mins on the turbo or rollers, gel on the start line.
With your intervals/TT etc before hand you effectively tried to do a stage race without the fitness/race knowledge and experience to back that up effectively.
Depending on how long you've been training for, it might just be you aren't fit enough at the moment (no bad thing if you are looking to race on a regular basis til September IMO).
I think road racing attracts a certain type of personality too - you have to be able to pick yourself up from getting dropped and keep going back for more no matter how humiliating it is (my coach and i got my taper badly wrong for the British National RR Champs which had Lizzie Armistead and the Wiggle Honda team in it, i got dropped before i should have and raced the remainder of the race in a 2 up round Glasgow city centre with EVERYONE i knew watching, it was so humiliating for me as my legs were simply too rested to work but i learnt a lot from that experience and came out of it stronger in the long run). Try things out, make mistakes and learn, all the time.