Welcome Peter.
Was your previous sibbing on inland waters or the sea?
Worth getting insurance as it's very cheap for your type/value of craft.... you never know when the unexpected might make you very pleased to have liability cover.
Re registration costs they vary greatly but if they are a requirement on the nearest and most pleasureable bit of water the overall costs of sibbing are so low compared to other activities I'd just get a licence and enjoy the outings.
No idea re costs but is this waterway any good as it's near to you...
http://www.rib.net/forum/f50/bodium-...tml#post762237 ??