www.direct.gov.uk will tell you a lot about public services and things in the UK.
Couple of things to note:
Register with the National health Service. It is free and you only need your passport showing your residence permit or your british passport if you've got one.
Register immediately with the local electoral registration office in your local council (where you reside), so that your name can be in the electoral roll/register. This is very important. Details are in the website above.
Refrain from applying for some things considered credit, such as store credit cards, bank credit cards, contract phone line, e.t.c. immediately you arrive (even if they offer the forms to you to fill). You are likely to be refused such if they do a credit check on you with the credit agencies and this would bring your rating down. Every search that results in decline brings down your credit rating. Until after you are registered in the electoral register, then the credit rating agencies can have a proper record of your address.
Do not be in a hurry to send your CV out to companies or recruitment agencies if you are looking for a job. Do it with careful thought. Any phone call you receive after you send out your CV is nearly always an informal interview and seems like a chat.
Some banks offer international accounts to new arrivals but you may need your bank statement from Nigeria to show your previous home address. (these accounts are not usually proper UK accounts, but will get you by for a while until you get a proper account)
You can apply for your National Insurance number if you have proof of evidence of looking for a job or if you have an employment letter. You will go for an interview to get this after scheduling an appointment and you will need some documents to carry along. They will tell you what to bring along when you book for the interview.
My working hours is 37 per week (I resume at 9am and close at 5pm with a lunch break)
Mortgage? Forget that side for now

. Come in, settle down, get a history in the country and mortgage will come later!
Tax and so on? Different bands of tax depending on how much you earn. Details are in the website above.
You can drive with your Nigerian drivers licence for only one year. You must stop driving immediately after the first year you arrived in the UK and have to get a Full UK driving licence to continue driving. The process and stress to get that one is another book chapter! Details are also in the website in motoring section.