let to buy advice please

I see there is another thread similar ot this and the advice is to go see an IFA which i am doing next week but am interested in view's of others, particularly anyone who has done this.

our current residential property we would like to let out, value is £140,000 will rent for £700 per month
We would be buying another property value £218,000.

Financially, I think it makes sense but my worry is the mortgages so here we go:

mortgage required on £218 property would be £70,000, on the let to buy it would be £103,000. My income is £33,000 per year with 3 dependants.

any ideas on if this is workable? any others with similar experience/situation?

Any out there who would just sell and therefore just have the one residential property with a smallish mortgage at about £35,000????

We would look at this as a long term investment and use an agent to manage (so up to £100 per month with the insurance etc..)

Any advice gratefully received.

thanks

David