At the end of the day though, most drill drivers would do the job if you pre-drill a suitably sized pilot hole first.
That is exactly what I was thinking. However, you can't deny that the impact driver can allow you to work quickly, without having to pre-drill pilot holes.
My original intention was to pre drill pilot holes and screw into them; even with an impact driver, this may still be necessary, but the impact driver would make life ALOT easier when it comes to driving in big screws into timber. I won't know until I try, but the impact driver might negate the need for pilot holes, which will make my life much easier.
I can either get the £40 drill/driver from Screwfix OR I spend an extra £35 and get the AEG impact driver. I didnt want to spend £73 on another drill, but I think I may not have a choice, given that I will be working with thick screws.