Hi, Vince, welcome to the forum! I've just started my PhD (Music, Royal Holloway) and I feel a bit like you, i.e., not confident enough with my skills, my choice of topic (which seemed perfectly feasible when I wrote my research proposal but now seems HUGE...). I try not to worry much about it and I think that as soon as I get into a PhD routine, allowing time to socialize etc, it will be fine (or at least that's what I hope...).