Sorry Brian, but continued membership of the EU will indeed affect many areas of what is now governance of the UK from Westminster.
The policing of our country will be affected. Brussels wishes to take over many aspects of our policing and judiciary. Please read this for yourself here http://www.express.co.uk/news/politics/666387/EU-referendum-Brexit-Brussels-think-tank-Juncker-Europe-intelligence-agency
The NHS is going to be adversly affected by the TTIP trade agreement that the EU is pursuing in secret with the USA. Please read here for the details http://www.express.co.uk/news/politics/666769/save-nhs-eu-referendum-brexit-doctor-warn-Angus-Dalgleish
and also here http://www.express.co.uk/news/uk/666454/NHS-EU-killed-off-Brexit-Remain-Leave-referendum-Brussels-European-Union
the EU wants TTIP to go ahead, and the provisions in TTIP will bring about an end to the NHS as we know it.
Surely control of our own Armed Forces should indeed be a domestic matter. At the moment it is, but the EU wants to progressively take over control of that as well. Cameron and Co have been denying for a long time that there is intent to create an EU Army, but now we know that they have been wilfully deceiving us. Here is the proof. https://www.youtube.com/watch?v=qyO2waEcVn0&feature=youtu.be
We are not even able to set our own rates of VAT in the UK without permission from Brussels. If that is not Brussels interference in UK taxation then I don't know what is. I presume you are familiar with the recent issue known colloquially as the 'Tampon Tax' ?
The above issues are not raised as a matter of my opinion or conjecture. They are hard facts. Read the references for yourself. Consider the reputable sources and the documentary evidence coming from the EU itself which supports these realities.
I know that you will say that each EU member country has a veto, and that is true at the moment. However, have you not read the EU Five Presidents Report of 2015 ? This report sets out the roadmap to ending the requirement for unanimity of all member states, and the instigation of qualified majority voting instead. Cutting through the jargon, what that means is the end of the veto. Without the veto, the UK can, and will often be simply outvoted. Again, this is not conjecture or opinion, but hard fact from the EU's own files. Therefore the only way to stop an eventual complete takeover of the UK by Brussels is to vote LEAVE.
If we stay in the EU, then it won't be long before no-one will be able to vote for MPs at Westminster, simply because there will not be any meaningful Parliament at Westminster to elect members of.