Have a look at Sportsdirect for not overly technical basic stuff in the sale.
Not sure how heavy this is but for £9.99 it's worth a try:
http://www.sportsdirect.com/airwalk-all-over-print-panel-jacket-mens-607168
Fot the same price there are also various padded gilets:
http://www.sportsdirect.com/no-fear-4ever-gilet-mens-608076
(and other brands/colours)
This one is looking quite light:
http://www.sportsdirect.com/no-fear-thriller-jacket-mens-608054
A quilted jacket that doesn't have the puffer look:
http://www.sportsdirect.com/lee-cooper-quilted-bomber-jacket-mens-607180
That last one is looking quite comfy for the use described, and still only £15!
Roos
Edited: 20/04/2012 at 18:48