In reply to Denni:
My daughters have both got a Vango Stratos 250W, which is a women's-specific bag. Slightly different shape to a men's bag and has a fleece-lined foot for extra warmth.
Would recommend if you can still get one, as not a current model. Looks like plenty on eBay well within your budget.
Downside is they are slightly on the bulky side, but not ridiculous if she needs the warmth.
Looks liks the replacement for it is the Stratos Alpha 250s - listed on Cotswolds for £57.50
Another option would be to see what down bag you can pick up on eBay within your budget - lighter to carry, but could be a disaster if it's a wet weekend.
Remind her to have a good hot dinner in the evening.
PS: Vango have a DofE recommended kit page on their website
Post edited at 09:18