I'm told that Provado have a product which treats for lily beetle, but I've never tried it. Otherwise control is by stealthy vigilence- inspect regularly, catch and snap the back of any beetles you find.
For the blackspot - buy some Roseclear 3 and a sprayer, mix up to the right strength for fungal infections (which is what black spot is) and spray till run off. Also deals with aphids, etc, spray in the evenings preferably after bees have stopped working.

when you crush lily beetle use a tissue or something they will stain your fingers.

I always spray my roses at this time to prevent blackspot. Include the stems. If you see any blackspot get rid of the infected leaves and spray again. Get rid of any leaves that have fallen onto the ground. Do not compost them. Roseclear 3 is what I use too.

I agree with the above answer as I do exactly the same thing, and I have alo been told when watering, only water the base not the leaves. It seems to work.