You really need to understand exactly the value of the bonus points you will be receiving and whether it actually makes sense. If you get a value of 25 GPB in Avios points but end up paying 50 GBP more and get locked in, you may be better off booking somewhere else that not only offers better rates but has more favorable terms. Not saying the extra Avois points aren't a good deal--just that you have to be an informed consumer and look at it holistically.