I wish your Dad well in his recovery, just a thought, I know you are probably all fired up now, but I'm sure the unit needs money all year round, you might get more support (assuming you're thinking of a bike run) in the summer.
My IAM group did a John O'Groats to Lands End run in 24 hrs this summer and raised £10,000 (from that + an Elvis Night
)
Don't know how the fund raising was organised - but sounds like it was effective with just 3 bikes doing the run.