Also being new to kayaking, I may not be best qualified to comment, but I have many of the same issues and came to the conclusion, for storage reasons that inflatable/collapsible was the way to go.
I haven't taken delivery yet, but have recently bought an Advanced Elements AF2 convertible from the US. As standard it comes with an open top and can accommodate 2 adults and a small child (another personal requirement). There are optional decks to convert it to a traditional double or single which I have purchased. Also, to add some extra rigidity, I have bought an additional aluminium "backbone".
Through one the official UK dealers, this little lot would have cost around 800 quid. I got this package for 749USDollar delivered to an address in the US - under half the UK price. This avoids the import tax and VAT which would have come to around 150 quid. Decathlon also have the basic kayak for £549 at Canada Water.
Advanced Elements website is
http://www.advancedelements.com/
The dealer I used is:
http://www.airkayaks.com/ae1007-07.html#System%20Bundles
When I have the boat back in the UK, I can bring it along one Tuesday night if anyone is interested in taking a look at this weird beast!
Cheers
Jim