Hi photovore, and welcome to Flyertalk!

Lots of more knowledgeable people than me will be along shortly to offer advice, but one thing to remember with Avios is that the number you need is directly related to the number of segments you fly, i.e. they are all priced individually. The programme operates differently to many of the North American programmes which charge you between two points with as many stopovers as you need in between (you may be aware of this already).

It will be tricky to avoid fuel surcharges because of the way BA charges these on redemptions, but the recent thread I've linked to below has what look to be some useful options for premium cabin redemptions which you may be able to work into your itinerary (e.g. flying to DUS on Air Berlin for 60k Avios + £3)

Are Avios good for ANY premium cabin redemptions anymore?

Good luck!