There are some very good online courses where you could read articles, watch videos and ask questions of other students and course leaders on forums like this one.
Some of them give certificates at the end but you could use them as practice for completing your officially recognised qualifications. For Example https://alison.com/learn/maths or https://www.futurelearn.com/courses/numeracy-skills.
Something like that you could do in your spare time at your own pace and then return to gain your official qualification with more confidence knowing that any interaction with your fellow students would be like here. Where your anxiety levels are hopefully not as high.