Assuming you don't have status on BA, then you will get the possible option of getting them at online check-in, 24 hours before departure. If you call 48 hours before departure, you may also get them, possibly, however in WTP it is also very possible that a parent and child will want that seat.

I wouldn't rely on seatguru, it has numerous errors in it, it is essentially an advertising sink site. thebasource.com is much better on the whole.

In particular, the idea that bulkheads are good in WTP is very much open to question - you should find a thread elsewhere in this forum relating to your aircraft type with more details - but essentially the design of WTP means you normally have more legroom away from the bulkheads, indeed some people strive to get the final row in WTP. You do get more kneeroom in the bulkheads though less legroom, but the spacing in WTP isn't as constrained as normal World Traveller / economy seating around the knee. The case for bulkheads is more for single travellers, rather than couples, since there is some possibility of the window seat person getting out without too much disturbance to the aisle passenger. But you're travelling in company so that doesn't really apply.