OK, the Beat injectors are on a common rail, so you'll need to unbolt all three injectors so that you don't undo any of the fuel or electrical connections. Point the injectors in to a dry container and turn the engine over for a few seconds, you should be getting a spray of fuel from each. Please remember that this is petrol, so don't crank it forever as you will be sending a combustible spray in to the air which could catch fire.

As you know you have a spark, the only other variable (provided you have not changed anything else) is the fuel. If you are not getting any fuel then it is likely that you have an ECU issue.

The other option is to borrow an ECU from another Beat. If it works you know that the ECU is the issue, and as it was (largely) working before the repair you'll know that the repair is the issue.

Re swapping another ECU, do you know any other Beat owners near Leeds?

Stu