if you leave your PRESENT system in service - you can use the plugs and lights while you work....

I'd start with a 100 amp 'basic house panel/breaker 'kit' form say Home depot. Actually .I've done this 3 -4 times.

The 'kit' has the box, main 100a breaker and  all the breakers you need to wire a basic house. Yes, 'overkill' for your shop... UNTIL.. you see that having LOTS of space and breakers gives you 'options'. The kitchen upgrade we did in 2000, has such a panel and 21 of the 24 breaker spots is USED !!! I thought I'd use 10-12 spots but the project 'grew' like wine fridge, dishwasher, OTC microwave, extra lighting(never used but... it's there ).

Nice thing is if you split up lighting onto several breakers, you can add new stuff or move things around and NOT be in the dark.

My garage/ workshop has 20 out of 24 spots filled. Arcwelder and air compressor are both 240 and either can be plugged into each others receptacle. Overhead lights (LEDs ) are grouped 2 per breaker, plugged into receptacles. Allows me to mount them where I want, easily moved  when I change the work tables around.

Extra spots allows for new circuits to be added,say when you get a drill press or furnace. I double boxed every bench location. With FOUR positions , I can plug in drill, trouble light AND battery charger as well as the X3 magnifier ....

Yes the upfront cost is there.... box full of breakers and the main feed cable BUT later additions will cost peanuts !

I did the same for neighbour who had FOUR, 15 amp runs to her garage. Replace with new panel, 12 breakers. NOW the garagedoor opener doesn't pop the overhead lights out.

NO, HE'D BE SECOND

1ST is make A PLAN ! Sit down , draw a sketch of shop,  layout where plugs and lights are needed.

Current Code will require a Second Service supply including a Meter Base to Just The Garage or IF can get the supply system company to do it change the Main Meter Base and transformer to a 1kv service drop then can run the second feeder triplex to the new second Service Box.  Electrician will be your Enemy/Friend to get it done properly.

Our Home and Workshop are fed from a 1Kv Service drop to a major Disconnect Switch, from there One Meter supplies the Bus Bar to feed the House on one leg and the shop on a second, there is space for a Third that I have segregated to a 50a Plug in Breaker protected drop at the disconnect bus for a Generator Connection.

100A Breaker (whoah)

My service panel for the pole barn is 100A 

And if you are gonna get an electrician involved, I think it should be up front.

Shop is the first load off the Meter Base, again 200a service box, Well and one side of shop HVAC is on that, had lathe and mill supplies as separate sourced breakers both at 40a 220v, my Air Compressor is 220 s.ph. and is on a 40a breaker yet a 50a outlet, all four welder outlets are separate and on 50a breakers yet I can only use one at a time as only me to run them.  Lighting and electrical outlets are separated, I feed a garden shed a parasite 120 service for two lamps and two outlets off the outlets in working/unheated side of shop.  Have plenty of service to add more heat just have not.  My barn in the valley has a 200a service box yet was purchased only as was handier than a 100a to achieve, is on its own meter.  Has a well, 3 welder and a air compressor outlets, three sets of 120 outlets inside, three large switched 120v overhead lamps and outside wall outlet banks.  Would rather have overkill than under capacity.