This is a question that is frequently asked and there would be a definite conflict of interest for a solicitor to represent both parties, things may be amenable now but they may not stay that way and circumstances change.
You may be better served if you have a separation agreement, which may be legally binding rather than separating informally if you use a solicitor to advise you on this or not, a separation agreement places in writing the important aspects of your agreements such as children, property and financial affairs, you can obtain draft separation agreements on line very cheaply You may also wish to consider a judicial separation, which involves the court who have the same power as in divorce but it does not dissolve the marriage so neither partner is free to remarry.