The chances of getting on that particular jury might be slim anyway
I went to Reading crown court last year on jury service, there was a pool of about 80 possible jurers, of which about 15/16 were called into court for each case.
In our case we were then asked if we had connections with, worked at, or knew anyone at a certain place of work. If we answered yes we were excused that case.
The clerk then selects 10 people trying to balance age, sex etc to produce a balanced jury, then the defendant has a chance to object to anyone.
Some people in our group never got to sit on a jury.
However bearing in mind Sod's Law, go for a deferment.
If after you accepted they came back to you and told you about a long case, then I'm sure so can defer, or at least not be considered for that case.
They don't want people on a jury of a long case that don't want to be there.