You can call Letsure or Maras to do simple credit checks on the prospective tenants, you'll be charged for it but it can be done. You will need to state your case as a Landlord as credit checking individuals as a simple citizen is hard to do and you’ll need the tenants approval too (often there at the time you call the companies. Both companies I've suggested have been in the industry for well over 25years and are very well respected. One thing they can't do is guarantee any prospective tenant, you have to decide on the information provided whether you want the tenant or not and it’s only based on current employment, ccj’s, and previous accommodation electoral role checks and that’s about it. It’s upto you whether you decide to take the tenant or not don’t forget.
Any new installation of Gas equipment needs a new Gas Safety Check I'm afraid. Regardless of new/old replacement, existing checks will not suffice if it's been fitted faulty, it'll be your responsibility as a Landlord if anything happens to your tenants whilst they are living in your property.
There are far too many Tenancy Agreements out there for all to see and modify. The Landlords Association is a professional body looking after the interests of Landlords and Tenants alike, they publish free T'Agg's and they are all underwritten by them and approved by the Gov't. There are a few to choose from, you alone will have to decide which T'Agg fits your purpose.
All Letting Agents are not like the ones you have encountered. Most are very professional and trustworthy indeed and cater for a market that is often fraught with unhappy people caught in an unhappy environment, .What they can't do is cater for Human behaviour.
There are schemes out there that will guarantee rental incomes, they are costly but if you need that service it’s there, so too Landlords Insurance. This is a particular bugbear of Landlords, for some reason they expect tenants to pay for buildings insurance and that is simply not the case, it’s your property, you should look after it. The tenant is only responsible for any fixtures and fittings inside and any damage can be claimed for unless it’s fair wear and tear.* You can not insist a tenant takes out their own insurance, that’s for the tenant to decide upon, it’s the same as you deciding whether you take contents insurance out in your own home.
Disputes between Landlord and Tenant should be dealt with by an independent adjudicator and not fisticuffs between aggrieved parties, don’t forget the vast majority of the Law is on the tenants side in situations like this and for that reason it’s there to prevent Landlords oppressing tenants, Landlord must provide adequate notice to enter the proerty whilst the tenant is in situ, written only with a date of entry, it’s upto the tenant whether they are there or not, but you can not enter the property without the tenats consent. If any service notices are issued then the Law changes and you do have certain rights of entry. Look into this as S21’s can be hard to issue as a single Landlord, you may need legal help to clarify what you can and can not do.
* this is moot but in most occasions it’s light fittings, door handles, sinks, toilets, baths etc. but even these can be over ruled by a sympathetic Judge.
>>> This is the last bit of advice I give, I'm not getting into arguments or explainations, if you need further information I'd suggest those with questions seek out thier own answers from reputable sources. <<<