Hi, I am 30 years old and I have just recently been diagnosed as autistic. My first reaction was "yup, that makes sense" but I have that feeling of "what now?"
Does anyone have any advice for someone who's just had their diagnosis, or what steps you took? I appear quite highly functioning and I maybe have learned to mask a lot, but I find I'm always exhausted after work or socialising and I struggle with managing things like chores.
Congratulations on your diagnosis and welcome to the community! 
You might find the strategies here helpful in respect of exhaustion and coping with things like chores:
NAS - Autistic fatigue and burnout
After getting over the initial impact, my diagnosis turned out to be the start of a new journey of learning and adapting. I'd suggest taking extra care to be patient to, and kind with, yourself - and to take your time with processing everything.
The NAS has a great set of articles focused on "after diagnosis", including one covering how you might feel during the subsequent days / weeks / months, and others covering the kinds of support that you can access. You might find them helpful as a starting point:
NAS - How will I feel after receiving an autism diagnosis - includes perspectives from other autistic people
NAS - Other advice covering post-diagnosis - including:
Therapy or counselling are often recommended after a diagnosis, as a follow up action for your GP to arrange. If you prefer, depending on where you are in the UK, you might instead be able to self refer for talking therapy on the NHS.
Before arranging anything, you might find it helpful to borrow or buy this book, which includes discussion of various types of therapy and counselling, together with advice on choosing the right therapist or counsellor - all from an autistic person's viewpoint. Several of us here have found it very helpful:
The Autistic Survival Guide to Therapy
Finally, I'll just mention a couple of books that I and others have found helpful early on in our post-diagnosis journeys:
Self-Care for Autistic People: 100+ Ways to Recharge, De-Stress, and Unmask!
How to Be Autistic (free download currently available via this page)
HiCheemma and welcome 
It is a lot to take in even if you’ve had strong suspicions. I would say just take things slowly and feel your way into it. Do som research on masking/unmasking if you feel able to this might help you feel less exhausted .
Hope you settle in here soon.
