You are going to need to find someone who can have your dog on a regular basis, and depending on the firm you are working for, potentially beyond usual dog day care hours too.
I am not a lawyer, but I work in a law firm and I am in your position - single person with a dog (Dennis). I am incredibly fortunate that my parents look after Dennis when I have to go to work but I am only 6 weeks into being back working (and I only do 4 days a week) and I am already starting to think about what dog day care options I can have for when my parents can’t have him (eg when they are on holiday).
If your dog can be left at home on its own for periods of time, you may find a dog walker can pop in and collect it, walk it for a couple of hours and bring it home, but depending on your commute and working hours, you need to be mindful you could be leaving your dog for easily for 10-12 hours a day, and if your in a firm known for long working hours, that could easily be 14-16 hours, and therefore having someone who can have your dog for longer periods of time maybe fairer to your dog, especially if it’s used to you being at home.
I would invest the time into finding appropriate and flexible dog care providers if your family/friends can’t support you - the key will be finding a provider who can go beyond 8am-6pm and who can commit to five days a week. That isn’t going to be cheap though. Even at four days a week, my dog day care is going to end up over £500 a month.