In the UK, the terms of a will are handled by an executor. This is someone chosen by the person making the will to see that his/her wishes, as set out in the will, are carried out. It can be a friend or family member, but is usually the solicitor (lawyer) of the person making the will.
When someone dies, before doing anything else, the executor must, by law, apply for a 'grant of representation' (aka a 'grant of probate'.) This gives the executor the legal right to gather and dispose the deceased's money, goods, property etc. the 'estate.'
Next comes the question of taxation. In the UK, if a dead person's estate is valued at more than £325,000, the UK government must be paid tax a rate of 40% on any value over that amount. Say a distant aunt dies and leaves you her house, which is independently valued as being worth £530,000 (not unrealisitic considering UK property prices these days). The UK government would be owed £42,000 in Inheritance Tax ('Death Duties'), This amount is due, whether the property is sold, or not - i.e. if you choose to go and live in auntie's house, you still have to find the £42,000 inheritance tax for the UK government. The government doesn't care how the cash is raised. It just wants it. Inheritance tax must be paid within 6 months of the death of the deceased. It is possible to pay large amounts in installments over a 10 year period.
So, the executors would need to calculate the total value of the grandmother's estate, including any bank accounts, jewellery and other possessions, her house, the bakery (and all its assets - equipment, stock etc.) From this final value they would calculate the amount of Inheritance Tax owed and put into effect any measures necessary to raise that amount from the estate. Usually this means selling stuff, valuable items, property etc.
Next (Sorry it's not over yet) the executor must settle any unpaid debts left by the deceased. This includes, outstanding bills, loans, mortgages etc. Again, money may have to be realised from the estate and stuff sold to do this.
Finally, when all that has been done, the executor is free to distribute the estate, or what's left of it, to the beneficiaries named in the will. Sometimes, of course, the person inheriting a property might find that the executors have had to sell it in order to raise the cash to pay Inheritance Tax and settle any outstanding debts. In that case, they would receive a proportional share of the estate, based on the value of property as a proportion of the whole estate, applied to true value of the estate after tax,debts etc have been paid.
The beneficiary inheriting the property can elect not to have the property sold, but to keep it and pay the Inheritance Tax him/herself. If there's more than one beneficiary, the maths can get complicated as executors try to figure out what proportion of any tax and debts are owed by each beneficiary. The amount would depend on the proportion of the whole estate they inherit.
Your MC and her bakery would require at least a Food Premises Approval and Food Business Registration (licences) She would also have to ensure that her business abides by the Health & Safety legislation. Without any experience, I think it's only really feasible for your MC to take over the bakery if it comes with a skilled baker ( e.g. her dead grandmother's employee who agrees to stay on, or the grandmother's assistant who's able to take over.)
So, your MC would probably find herself owning a business which she doesn't know how to operate and probably owing the UK government quite a lot of money. If granny owned the bakery's premises, it would be worth well in excess of the £325,000 Inheritance Tax threshold. The cheapest bakery would probably be valued at around £500,000 (That's an Inheritance Tax bill of £70,000). A well-established, successful one is currently on the market in the NW of England, fully-equipped and ready to roll, at £1.8 million.