On-line ticket help

I'm going away for a few days soon (middle of May) and I was wondering how soon before I need to book flight tickets via the BA website and the train tickets from Bridgend to Heathrow. Has anyone booked the whole journey via the internet and, if so, did it work out for you and how much notice did you give? I will be doing this within the week of my travel

Nottage Blue i found that the bus was alot cheaper than the train on a last min booking to Heathrow £49 ret and pick up from sarn every hour