I had a Zero 1 layout in the 1980's and it was excellent then, but it's very old hat now.
I was going to suggest that ZTC do modules which are Zero 1 compatible, but then I saw that they (ZTC) have had 'problems'.
Someone else is handling their kit now. A Google throws up this linky...
http://www.sbxmodelrail.co.uk/Default.htm
To be honest Zero 1 is obsolescent. Since you've got some bits it might be worth a dabble for curiousity's sake, but don't spend too much cash on it. If you're seriously considering starting a new layout I'd suggest going for a DCC system, or similar.