Toggle Checkboxes On/off With Unique Id?

I'm using the following code to toggle checkbox checked and disabled attributes.

var f = false;
function tick(group) {
if (!f) {
for (var i=0, len = group.length; i < len; i++) {

[code]......

The checkbox doing the js call uses onclick="tick(country)" and the checkboxes that I want to toggle all have the same id e.g.

<label><input type='checkbox' name='uk[]' id='country' value='England' />England</label><br />
<label><input type='checkbox' name='uk[]' id='country' value='Scotland' />Scotland</label><br />

This all works correctly but does not validate.I need to use unique id's for each name.The easiest way (as each checkbox html is generated by php) is to append the value to the id i.e.

<label><input type='checkbox' name='uk[]' id='countryEngland' value='England' />England</label><br />
<label><input type='checkbox' name='uk[]' id='countryScotland' value='Scotland' />Scotland</label><br />

How can I modify the javascript function factor this in i.e. toggle where id contains country?