Is my landlord allowed to hand out my name and address to solicitors?

Unless your written lease (assuming you have one) with your landlord concerning the rental you have expressly prohibits him or her from providing solicitors your name and address without your knowledge or consent, your landlord can legally do what he or she did.

Whether your landlord used common sense in what was done by not first asking you about permission to do what was done is debatable.

You have an expectation of some privacy while renting from your landlord and what he or she did infringes upon your right to be left alone from unwanted solicitors. Unfortunately, what was done does not warrant a legal action. What the conduct warrants is a call from you to the landord with a follow up letter requesting that in the future, your name and address as well as other information concerning you not be provided to solicitors.

It may be the case that your landlord cannot give out the information as to the home security system. Certainly, he can give out your name and address: there is no privacy expectation in public information, and one's name and address is public information. It may be the case that he can't give out the information about the security system, since it might be the case that the average reasonable person would consider that private or confidential information and not want it given out; it's also not publically available, the way name and address are--thus, there *may* be a privacy expectation in it. Moreover, if it turns out that the "solicitor" is a scam and they are just trying to find out who does not have a security system so they can rob them later (that, by the way, is why there may be a legitimate privacy expectation in this information--the average person would not want strangers to know their home is vulnerable), you may be able to sue the landlord for his or her negligence in providing this information.