Direct - Parents is a good starting point to learning all the fun and wonderful world of parenting in the UK.
You don't need to prepare your son for nursery as such, but as Noreneh mentioned once he's 3 he'll qualify for
free early learning - depending on your council this can be between 12.5 - 15 hours free. From pesonal experience nursery is more like daycare than school as such, but each nursery will be different. But it is seen more as a stepping stone to prepare children for school.
Seeing as your son's 2 you may want to consider a preschool for him to attend a couple days a week just so you can find time to get yourself settled in as well, but that's up to you. My daughter turned 2 in November and was eligible to attend Preschool at the school we wanted then and there, but we opted to wait 'til January and have her start at the beginning of term. She goes twice a week (2.5 hrs per session) and absolutely loves it!
Once you've got a list of schools, carers or preschools as the case may be that you're looking at you may want to check their
Ofsted rating and report to help get more perspective.
Alternatively you may want to check out
NetMums to see what's available in your area (playgroups, nurseries, schools, activities etc). On the forums you can chat with other Mums in the area you'll be living in to gain a better perspective of the schools available and what they're really like.
Also, checkout your local
Sure Start Childrens Centre for activity groups for you and your son. They'll also be able to tell you of other toddler groups in your area as well as have a list of carers, preschools and daycares in the area.
Good luck!