A mask will not protect you unless it is of medical standard, properly fitted, changed VERY regularly, you NEVER touch it or touch your face, and you 'don and doff' it with utmost care.
In fact it will probably be counterproductive as most people will do none of the above.
However it will make it a little bit less likely that you will pass the virus on if you have it and you are pre-symptomatic or asymptomatic. I think it will be recommended in the UK if you are in a shop or on public transport where physical distancing is difficult or impossible.
I saw an elderly lady arrive home from the supermarket last week wearing rubber gloves. She struggled to get her key from her purse so she proceeded to use her teeth to pull each finger of her gloves one by one. She may as well have gone back to the shop and licked the keypad of the ATM. Gloves offer no more protection to the wearer than masks and possibly make it more likely they will get infected. Your skin is impervious to the virus.
Wash your hands, don't touch your face, respect physical distance and hope for the best.