Thanks everyone for your support and taking the time to reply, it really does mean a lot.
It's easy sometimes to get things out of perspective and to feel that if your peformance and drive are deteriorating, then it must be your fault for not training hard enough. With retrospect, I was much too hard on myself and lost sight of why I was riding and what I wanted from it.
It's interesting to hear that others have had similar experiences too - my self-enforced break DID do me the world of good, because now I'm enjoying being in the saddle again and just loving turning the cranks and pootling under my own steam.

It really is lovely to be back.