home insurance -still being dim!

On the locks, look at the bit where the bolts come out. Sounds like it is a mortice sash lock with a square bolt for deadlocking and a curved one for the handle. Have a look to see if it says "5 lever" and has a British Standard kitemark.

If it says 2 lever or 3 lever, it will not meet insurers requirements.

Contents cover will cover your liabilities if you damage a neighbours property, for instance, leaking washing machine or overflowing bath.

Window locks - can usually be retrofitted fairly easy on timber framed windows. Wide variety of styles to choose from. Virtually impossible to retfrofit to UPVC windows.
Metal framed windows can be done but only if you are comfortable with drilling and DIY.

You can get insured with the wrong locks (if you lie) but then run the risk of having a theft claim turned down if the thieves enter through that door and the lock wasn't of the required standard.

Couple of other things you can check though first.

1) what kind of key do you have? Is it a "lever" key where you have a round barrel and then the lock differs on the end. The differs are the bit that turn the lock inside. Or is it a flat key similar to the one you use in your Yale latch?
If it is the first, you have a lever sash lock which is the same as a lever mortice dead lock. If the latter, it is a cylinder operated sash lock and these are becoming more common now (people prefer the smaller keys).

2) Next check the frame side of the door where the bolt work enters a hole in the frame. Is this covered with a flat metal plate or is it a metal plate with a metal box behind it? If the latter, that is called a box striking plate and they are normally fitted to locks that meet the British Standard.

To give you an idea what I'm on about have a look at these sites.
http://www.yalelock.com/Yale/Templates/HowToSecureHome____3345.aspx
http://www.chubblocks.co.uk/secureproperty.html

Insurers will normally ask for a 5 lever mortice dead lock. The 5 levers give the lock well in excess of 1000 key variations whereas 2 lever has about 20 variations. The 5 lever locks in conjunction with a box striking plate will hold against 1 tonne of force (although the door itself usually gives up before this).

It is in the housing associations interests to improve the security so they should allow an upgrade. Approved locks can be purchased in sizes to suit all door types and are usually a direct replacement for the existing. There is a bit of chisseling involved though because of the extra thickness of the drill resisting side plates and the box striking plate in the frame. In Cambridgeshire for example, a locksmith would charge around £40-50 to fit plus the cost of the lock.