Diesel is 54p/litre at our local Safeway supermarket, and we're complaining. FWIW here's a table of fuel prices at Flying J truck stops across the U.S. The table is continually updated. Prices are in $US per US gallon, so divide by 2 for pounds, and 1 US gallon = 3.785 litres.
If you click the Choose province link, you can view prices in Canada. They'll be in $CDN per litre.
The answer to this question is YES you can.
IF IT RUNS ON DIESEL IT RUNS BETTER ON BIODIESEL!!
Any diesel vehicle or diesel engine can run using biodiesel and NO modification is required to modern day cars, vans or trucks (you can also use biodiesel in boats, boilers, generators and heaters).
Biodiesel will prolong the life of your engine as it is very lubricious and even used in very low mix percentages it can reduce engine wear substantially.
The transition is seamless; you simply use biodiesel as a replacement or in addition to your standard fuel. It can be used in its pure form (B100) or blended with fossil diesel in any percentage.
The price you pay includes the applicable excise duty and VAT so you can also rest assured you are driving perfectly legally.
There are a couple of points to note.
Biodiesel is very good at cleaning your engine and removing the build up of resins and deposits that have built up with standard diesel usage so you may notice a reduction in performance after driving 200 miles or so this is because the biodiesel will have dissolved the resins and deposits in your fuel tank and fuel pipes and deposited these in your fuel filter, all you need do is change your filter (a very minor and inexpensive job) and you can now run on biodiesel for ever more.
If your vehicle is very old i.e. over 13 years old and your fuel pipes are made of rubber you will need to change these to modern polythene pipes to avoid the rubber breaking down with the biodiesel use (all modern diesel vehicles have polythene pipes fitted as standard).
If you revert to normal diesel use and then back to biodiesel you may need to change your fuel filter again.