Whether you draft your will entirely independently or decide to use a professional service (such as a solicitor or will-writer), I strongly advise preparing a very basic draft first yourself. The first will I had drawn up was done by a solicitor but I realised years later (when I set up my own will-writing business) that he'd not asked the type of questions that I then thought that he really should have done. (e.g. "What should happen if Beneficiary X dies before you do?").
So start by writing down who you wish to be the executors of your estate. (You can have as many as you like but most people choose to have either one or two). Then write down what should happen if an executor dies before you do.
Next write down your funeral wishes. (They're not actually binding on your executors though).
Then move onto how your estate should be dealt with and divided. (e.g. should everything be sold and the money distributed according to your wishes or should certain things remain unsold and be given to specific beneficiaries).
Next, give some consideration as to what should happen to a gift in your will if a named beneficiary dies before you do.
Remember that anything you might leave to a minor will need to be left in trust, so write down who the trustees should be in such circumstances
Take some time to think through anything else that you need to consider.
Then, and only then, draft your will yourself or take it to a professional to deal with. If you simply turn up at a solicitor's office, without prior preparation, there's a very good chance that something will get left out.
Here's a draft will that I prepared for Caran, who wanted to leave everything to her niece. (There's absolutely no personal information in it, so I'm not breaching Caran's privacy in any way here):
https://easyupload.io/kk5agc
It might give you an idea as to what you should be working towards.