Support bubble/chilcare question

During this second lockdown we’ve been really strict. Not seeing anyone, working from home and getting things delivered etc. I wanted my Mum to visit after this lockdown to give me a hand though. I am 30 weeks pregnant and have a 20 month old. Our house is just crazy and I have so much to prepare before the arrival of our newborn.

Is it legal for me to to ask my parents to stay for 2 nights to help with childcare whilst I sort everything out? We live 3hrs away from any kind of family support. Life isn’t easy! They also live in a very low Covid area (some days there have been no cases), whereas we live in a highly effected area. I don’t want to put them at risk, but then again - we’ve been so careful because I’m pregnant, so they are happy to make the journey and lend a hand.

I am completely confused by the restrictions, the bubbles, the childcare bubbles and Mothers with children of pre school age especially. Please can anyone shed some light on where I stand with getting help? Thank you.