I'm a solo mother by choice (IVF using a sperm donor), so I went into this knowing I'd be doing it all alone so to speak.
What is your work situation? Will you be on SMP or Maternity Allowance package? And how long are you taking your maternity leave for? Is your housing situation secure (enough)?
You will be very busy with the baby once it arrives, I was for at least the first 3 to 4 months. Having a baby is an enormous emotional and physical adjustment, nothing quite prepares you for it. It was very intense in the beginning and with broken up sleep, meeting new people I didn't know simply wasn't a priority because that took time and energy and effort I didn't have capacity for. Friends and family may or may not step up once the baby arrives, so right now assume that you will be 100% doing it all alone. Some may surprise you others disappoint you, but you will find your own rhythm with the baby eventually and things will get easier bit by bit as they get older.
Personally, I found the "baby/mummy" apps to be a waste of time, just a another platform to join/chat a little bit no real progress in terms of meeting up, forming a level of friendship etc. Everyone is busy with their babies etc and they'd prioritise real-life friends over randoms they'd met on the app. What seems to have worked best for me is attending local (free) playgroups run by the council, and I've made a new "mummy" friend from my baby swimming class (not free). Meeting people in real life when I felt ready and confident was a game changer in terms of socialising. I do keep in touch/meet up in person with my friends ore child too as there is a more established connection there which has nothing to do with being a parent. And when you go back to work, you may get the opportunity to socialise with your colleagues too.
I hope this helps a little Op @Chhesyte