The CAA Licensing rules (see LASORS) mandates classroom learning. There are a certain number of study hours required and the only way the CAA can be sure this is achieved is by making groundschool compulsory. So all Distance Learning groundschool providers will operate the same way.
The only way around it would be to have ATPL exams from another state and convert but even, you would have to attend in another country!
Have you considered CPL exams - there are fewer and will therefore require less time off work?
Depends what you want the licence for? You may have to sacrifice some unpaid leave if ATPL is the only one you want to get.
Cheers
Whirlygig