Geoff: the standard arrangement here is to lose Good Friday instead.

looks as though i may be flying. on the rail europe site and through the reservationist at rail europe while ordering tickets i was led to belive that there would be the train service i stated previously. seems i may have misinformed, but thanks to all of you my trip will be saved! any thoughts or suggestions on the transfer from heathrow to the eurostar? again thank you all very much!!

You could just fly Edinburgh-Brussels, although not on the 26th; you'd have to wait until the 27th. bmi has a direct flight at 13.35 currently showing as £47 one way + taxes etc of £22.70 = £69.70. It would seem a lot easier than the hassle of trying to get around using multiple forms of transport on Boxing Day.

Alternatively get the overnight Superfast ferry from Rosyth (just across the Forth from Edinburgh & they run a bus from the city) to Zeebrugge - see www.superfast.com. The boats are lovely although I admit I've only done the journey in the summer. The website doesn't seem to say whether the (usually daily) service takes any breaks for Christmas, though, so you may need to e-mail them to ask.

Heathrow to Waterloo:
1. Cheapest (3.80 GBP). Take the tube (Piccadilly Line) to Piccadilly Circus. Change to the Bakerloo Line and take it to Waterloo. Travel time is approx. one hour.
2. Fastest. Take the Heathrow Express to Paddington Station (13.00 GBP). Take the Bakerloo Line to Waterloo (2.00 GBP).

continuing above post
3. The fastest way - take a taxi to Feltham train station (within eyeshot of Heathrow Terminal 4) and then take twice an hour trains right into Waterloo - quickest and easiest. There is a Rail bus that runs from Heathrow terminals to Feltham but it takes forever as it has to navigate around the airport.
As for original post. Are you sure there are trains running from Edinburgh on Dec 26 - very few trains run in UK on Boxing Day i believe. As for making connections, the UK high-street betting parlors would not give you very good odds at making the connection - train from Edinburgh is likely to be late!